Conservative firebrand Andrew Breitbart dies at age 43

The conservative blog star was mourned today by the Republican presidential candidates. He died at the age of 43 after collapsing on the sidewalk near his Southern California home. NBC's Andrea Mitchell reports.

By msnbc.com staff and news services

Caustic commentator Andrew Breitbart was loved by conservatives who championed his viral Internet exposes that brought down politicians, and hated by others who said he selectively used the truth to do it.

The conservative media publisher and activist who died Thursday at 43 was embraced by anti-tax, conservative tea partiers and reviled by liberals for his Internet investigations that led to the resignations of former New York Rep. Anthony Weiner and former U.S. Agriculture Department official Shirley Sherrod.

According to the Associated Press, Breitbart was walking near his house in the Brentwood neighborhood shortly after midnight Thursday when he collapsed, his father-in-law Orson Bean said. Larry Dietz, watch commander at the Los Angeles County coroner's office, said a cause of death was unknown and an autopsy was likely. Breitbart had suffered heart problems previously. Breitbart's website, bigjournalism.com, said Thursday he died of natural causes.

Someone saw him fall and called paramedics, who tried to revive him. They rushed him to the emergency room at UCLA Medical Center, Bean said. Breitbart had suffered heart problems a year earlier, but Bean said he could not pinpoint what happened.

"I don't know what to say. It's devastating," Bean told The Associated Press. He is survived by his wife Susannah Bean Breitbart, 41, and four children.

Breitbart, in addition to publishing a number of websites devoted to repudiating what he saw as the liberal-dominated coverage of politics and culture, once served as an editor for the Drudge Report and helped Arianna Huffington launch the Huffington Post website.

In addition to his Web properties, Breitbart was also very active on Twitter, where he often retweeted criticism from some of his harshest critics. The last tweet from his account was from late Wednesday.

Following news of his death, Breitbart's name shot to the top of Twitter trends.

In addition, a number of Republican lawmakers tweeted their sympathies.

Eric Cantor ‏ @EricCantor I'm stunned to hear about the passing of Andrew Breitbart. My thoughts and prayers are with his wife Susie, his children, and his friends

Media Matters, the liberal watchdog that was a frequent Breitbart critic, said the organization's "thoughts and prayers are with his family today."

"We've disagreed more than we've found common ground, but there was never any question of Andrew's passion for and commitment to what he believed," said Media Matters' Ari Rabin-Havt.

Republican presidential contenders also weighed in.

Rick Santorum called Breitbart a "powerful force" after learning of his death from reporters at a rally in Dalton, Ga. "He will be what a huge loss ... for our country and certainly for the conservative movement and my prayers go out to his family," Santorum told reporters. "I'm really sorry to hear it."

Mitt Romney posted to Twitter: "Ann and I are deeply saddened by the passing of (at)AndrewBreitbart: brilliant entrepreneur, fearless conservative, loving husband and father."

Newt Gingrich tweeted: "Andrew Breitbart was the most innovative pioneer in conservative activist social media in America. He had great courage and creativity."

Breitbart's fans have praised him for exposing government corruption and media bias.

Breitbart also sparked a controversy that ultimately led to the resignation Weiner, whose problems began on May 28 when Bretibart's biggovernment.com posted a lewd photograph of an underwear-clad crotch and said it had been sent from Weiner's Twitter account to a Seattle woman.

Initially, Weiner lied, saying his account had been hacked. But he pointedly did not report the incident to law enforcement — a step that could have led the way to charges of wrongdoing far more serious than mere sexting.

Additionally, his public denials were less than solid — particularly when he told an interviewer that he could not "say with certitude" that he wasn't the man in the underwear photo.

Weiner's spokesman said the photo was just "a distraction" and that the congressman "doesn't know the person named by the hacker."

The congressman denied sending the photo and said he had retained an attorney and hired a private security company to figure out how someone could pull off such a prank.

But Weiner dropped that story line on June 6, offering a lengthy public confession at a Manhattan news conference, acknowledging to online activity involving at least six women.

Breitbart seldom showed restraint in his vitriol to his critics and seemed to relish in the negative attention his antics earned him.

After Sen. Edward M. Kennedy of Massachusetts died in 2009, Breitbart tweeted "Rest in Chappaquiddick" and called him "a special pile of human excrement." When critics questioned his tone, he tweeted they "missed my best ones!"